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Regeneration Rate (regeneration + rate)
Selected AbstractsRegeneration potential of CIMMYT durum wheat and triticale varieties from immature embryosPLANT BREEDING, Issue 4 2001N. E. Bohorova Abstract Twenty-five durum wheat elite advanced lines and released varieties, and five triticale varieties were evaluated for their ability to produce embryogenic callus using three different media. For callus initiation and maintenance there were basal Murashige and Skoog (MS) medium containing double strains of macroelements and 2.5 mg/l 2,4D (DW1), basal MS medium containing 2.0 mg/l 2,4D (DW2), or basal MS medium supplemented with 1.0 mg/l 2,4 D and coconut milk (DW3). Plant regeneration was achieved on basal MS medium with indoleacetic acid and 6-benzylaminopurine, and plants rooted on MS with 1-naphthale-neacetic acid. DW3 medium proved better than the other media tested for embryogenic callus initiation and maintenance. Regeneration rates varied widely with both genotype and initiation medium, with values ranging from no regeneration to 100% regeneration; the plantlets produced per embryo ranged from five to 20. Fourteen of the durum wheat genotypes showed 63,100% regeneration from DW3 callus formation medium, four lines from DW1 medium, and two lines from DW2. Four of the triticale varieties had regeneration of 48,100% from DW3 medium. After six subcultures, over a 6-month period, genotypes lost their ability to regenerate plants. Only 10 lines retained some plant regeneration potential but regeneration was at reduced levels. Successful regeneration of durum wheat and triticale varieties will be used as an integral part of the transformation process. [source] Retroviral labeling of Schwann cells: In vitro characterization and in vivo transplantation to improve peripheral nerve regenerationGLIA, Issue 1 2001Afshin Mosahebi Abstract Transplantation of Schwann cells (SCs) is a promising treatment modality to improve neuronal regeneration. Identification of the transplanted cells is an important step when studying the development of this method. Genetic labeling is the most stable and reliable method of cell identification, but it is still unclear whether it has deleterious effect on SC characteristics. Our aim was to achieve a stable population of SCs transduced with the lacZ gene at a high frequency using a retroviral vector in vitro, and to follow the labeled SC in vitro to assess their viability and phenotypic marker expression. Furthermore, we transplanted lacZ -labeled SCs in a conduit to repair peripheral nerve to investigate their effect on nerve regeneration in vivo. Rat and human SCs were cultured and transduced with an MFG lacZ nls marker gene, achieving a transduction rate of 80% and 70%, respectively. Rat SCs were kept in culture for 27 weeks and examined every 4 weeks for expression of lacZ, viability, and phenotypic marker expression of GFAP, p75, MHC I and II. Throughout this period, transduced rat SCs remained viable and continued to proliferate. The proportion of cells expressing lacZ dropped only by 10% and the expression of phenotypic markers remained stable. Transduced human SCs were followed up for 4 weeks in culture. They proliferated and continued to express the lacZ gene and phenotypic marker expression of GFAP and p75 was preserved. Primary culture of transduced rat SCs were transplanted, syngeneically, in a conduit to bridge a 10 mm gap in sciatic nerve and the grafts were examined after 3 weeks for the presence and participation of labeled SCs and for axonal regeneration distance. Transplanted transduced rat SCs were clearly identified, taking part in the regeneration process and enhancing the axonal regeneration rate by 100% (at the optimal concentration) compared to conduits without SCs. Thus, retroviral introduction of lacZ gene has no deleterious effect on SCs in vitro and these SCs take part and enhance nerve regeneration in vivo. GLIA 34:8,17, 2001. © 2001 Wiley-Liss, Inc. [source] Comparative study between parallel and counter flow configurations between air and falling film desiccant in the presence of nanoparticle suspensionsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2003A. Ali Abstract A comparative numerical study is employed to investigate the heat and mass transfer between air and falling film desiccant in parallel and counter flow configurations. Nanoparticles suspensions are added to the falling film desiccant to study heat and mass transfer enhancements. The numerical results show that the parallel flow channel provides better dehumidification and cooling processes of the air than counter flow configuration for a wide range of pertinent parameters. Low air Reynolds number enhances the dehumidification and cooling rates of the air and high air Reynolds number improves the regeneration rate of the liquid desiccant. An increase in the channel height results in enhancing the dehumidification and cooling processes of air and regeneration rate of liquid desiccant. The dehumidification and cooling rates of air are improved with an increase in the volume fraction of nanoparticles and dispersion factor. Copyright © 2003 John Wiley & Sons, Ltd. [source] Size-dependence of growth and mortality influence the shade tolerance of trees in a lowland temperate rain forestJOURNAL OF ECOLOGY, Issue 4 2009Georges Kunstler Summary 1A trade-off between growth in high-light and survival in low-light of species is often proposed as a key mechanism underpinning the dynamics of trees in forest communities. Yet, growth and survival are known to depend on plant size and few studies have analysed how this trade-off can vary between juvenile life stages and the potential consequences of the trade-off for the differences in regeneration rate between species in mixed forests. 2We quantified growth and mortality for two different juvenile life stages , seedlings and saplings , of seven tree species common in temperate rain forests in New Zealand using data from field studies. We found strong evidence that the ranking of species for survival in shade and growth in full light was affected by size. There was a trade-off between seedling survival in low light and sapling height growth in high light, but no trade-offs were observed when considering other combinations of life stages (seedling growth vs. seedling survival, seedling growth vs. sapling survival, or sapling growth vs. sapling survival). 3We ran simulations with an individual-based forest dynamics model , SORTIE/NZ , to explore how the trade-off drives the differences in tree species regeneration success in gaps vs. under closed forest conditions. These simulations indicate that because species' ranks in shade tolerance varied with life stage, regeneration success was not predicted from knowledge of tree performance at a single life stage. For instance, high-light sapling growth was a strong determinant of regeneration success in forest gaps, but seedling growth was also influential. Under closed forest, regeneration success was primarily limited by low-light mortality at the seedling stage, but seedling growth and sapling survival were also influential. 4Synthesis. Growth-survival trade-offs can be strongly affected by the size of the individual analysed, resulting in completely different rankings of the shade tolerance of species across different juvenile life stages. Performance of both seedlings and saplings influenced regeneration success, highlighting the need to consider growth-survival trade-offs and the shade-tolerance strategies of tree species over a large range of juvenile sizes. [source] Infrared Radiation Influence on Molt and Regeneration of Neohelice granulata Dana, 1851 (Grapsidae, Sesarminae)PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2009Vinícius Cunha Gonzalez This paper analyzes the influence of infrared radiation (IR) on regeneration, after autotomy of limb buds of Neohelice granulata and consequently the time molt. Eyestalks were ablated to synchronize the start of molt. Afterward, animals were autotomized of five pereopods and divided into control and irradiated groups. The irradiated group was treated for 30 min daily until molt. Limb buds from five animals of days 4, 16 and 20 were collected and histological sections were made from them. These sections were photographed and chitin and epithelium content measured. Another group was made, and after 15 days limb buds were extracted to analyze mitochondrial enzymatic activity from complex I and II. The irradiated group showed a significant reduction in molt time (19.38 ± 1.22 days) compared with the control group (32.69 ± 1.57 days) and also a significant increase in mitochondrial complex I (388.9 ± 27.94%) and II (175.63 ± 7.66%) in the irradiated group when compared with the control group (100 ± 17.90; 100 ± 7.82, respectively). However, these effects were not acompanied by histological alterations in relation to chitin and epithelium. This way, it was possible to demonstrate that IR increases complex I and II activity, reduces the time molt and consequently increases the appendage regeneration rate. [source] Liver Graft Regeneration in Right Lobe Adult Living Donor Liver TransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 6 2009Y.-F. Cheng Optimal portal flow is one of the essentials in adequate liver function, graft regeneration and outcome of the graft after right lobe adult living donor liver transplantation (ALDLT). The relations among factors that cause sufficient liver graft regeneration are still unclear. The aim of this study is to evaluate the potential predisposing factors that encourage liver graft regeneration after ALDLT. The study population consisted of right lobe ALDLT recipients from Chang Gung Memorial Hospital-Kaohsiung Medical Center, Taiwan. The records, preoperative images, postoperative Doppler ultrasound evaluation and computed tomography studies performed 6 months after transplant were reviewed. The volume of the graft 6 months after transplant divided by the standard liver volume was calculated as the regeneration ratio. The predisposing risk factors were compiled from statistical analyses and included age, recipient body weight, native liver disease, spleen size before transplant, patency of the hepatic venous graft, graft weight-to-recipient weight ratio (GRWR), posttransplant portal flow, vascular and biliary complications and rejection. One hundred forty-five recipients were enrolled in this study. The liver graft regeneration ratio was 91.2 ± 12.6% (range, 58,151). The size of the spleen (p = 0.00015), total portal flow and GRWR (p = 0.005) were linearly correlated with the regeneration rate. Patency of the hepatic venous tributary reconstructed was positively correlated to graft regeneration and was statistically significant (p = 0.017). Splenic artery ligation was advantageous to promote liver regeneration in specific cases but splenectomy did not show any positive advantage. Spleen size is a major factor contributing to portal flow and may directly trigger regeneration after transplant. Control of sufficient portal flow and adequate hepatic outflow are important factors in graft regeneration. [source] Factors affecting adventitious regeneration from in vitro leaf explants of ,Improved French' plum, the most important dried plum cultivar in the USAANNALS OF APPLIED BIOLOGY, Issue 1 2010C. Petri An adventitious shoot regeneration protocol from in vitro leaves of the most important dried plum cultivar in the USA, ,Improved French', has been established. Factors affecting regeneration were studied in order to optimise regeneration. The proliferation medium in which the shoots, used as the source of leaf explants, were cultured had a strong influence on subsequent regeneration. Shoot regeneration was observed at a mean frequency of 52% when a Murashige-based and Skoog-based shoot culture medium with 3 ,M N6 -benzylaminopurine and 0.25 ,M indole-3-butyric acid (IBA) was employed compared with shoot regeneration frequencies of less than 5% for a Quoirin-based and Lepoivre-based shoot culture medium, with 8.9 ,M N6 -benzylaminopurine and 0.49 ,M IBA. The shoot regeneration medium contained ,-naphthaleneacetic acid at 2.0,6.0 ,M and thidiazuron at 4.5,15.0 ,M. 2,4 Dichlorophenoxy-acetic acid at 9.0 ,M was included in the medium but only for the first 4 days of culture. Shoot regeneration frequencies were positively related to thidiazuron concentration and significantly greater (P < 0.05) for 9,15 ,M thidiazuron than for the media with 4.5 ,M thidiazuron. Leaf explants, incubated in a 16-h-light/8-h-dark photoperiod or in the dark for 1 week followed by exposure to light, showed significantly more organogenic activity (P < 0.01) than was observed for leaves cultured in the dark for 2 or 3 weeks before they were transferred to the light. The utilisation of Bacto agar (0.7%) as the gelling agent increased organogenesis compared with media gelled with TC Agar (0.7%), or an agar,gellan gum blend (AgargelÔ) (0.45%). The addition of the ethylene inhibitor silver thiosulphate at 60,120 ,M also improved organogenesis. When all the studied factors were optimised, a regeneration rate of 65% was achieved. Rooting frequency of regenerated shoots was significantly increased (P < 0.05) by the use of full-strength Murashige and Skoog salts (40%) or 100 mg L,1 phloroglucinol (53%) to the rooting medium. [source] Liver regeneration after major hepatectomy for biliary cancerBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 8 2001Dr M. Nagino Background: The aim of this study was to evaluate serial changes in liver volume after major hepatectomy for biliary cancer and to elucidate clinical factors influencing liver regeneration. Methods: , Serial changes in liver volume were determined, using computed tomography, in 81 patients with biliary cancer who underwent right hepatic lobectomy or more extensive liver resection with or without portal vein resection and/or pancreatoduodenectomy. Possible factors influencing liver regeneration were evaluated by univariate and multivariate analyses. Results: The remnant mean(s.d.) liver volume was 41(8) per cent straight after hepatectomy. This increased rapidly to 59(9) per cent within 2 weeks, then increased more slowly, finally reaching a plateau at 74(12) per cent about 1 year after hepatectomy. The regeneration rate within the first 2 weeks was 16(8) cm3/day and was not related to the extent of posthepatectomy liver dysfunction. On multivariate analysis, the extent of liver resection (P < 0·001), body surface area (P = 0·02), combined portal vein resection (P = 0·024) and preoperative portal vein embolization (P = 0·047) were significantly associated with the liver regeneration rate within the first 2 weeks. In addition, body surface area (P < 0·001) and liver function expressed as plasma clearance rate of indocyanine green (P = 0·01) were significant determinants of final liver volume 1 year after hepatectomy. Conclusion: The liver regenerates rapidly in the first 2 weeks after major hepatectomy for biliary cancer. This early regeneration is influenced by four clinical factors. Thereafter, liver regeneration progresses slowly and stops when the liver is three-quarters of its original volume, approximately 6 months to 1 year after hepatectomy. © 2001 British Journal of Surgery Society Ltd [source] Debating the greening vs. browning of the North American boreal forest: differences between satellite datasetsGLOBAL CHANGE BIOLOGY, Issue 2 2010DOMINGO ALCARAZ-SEGURA Abstract A number of remote sensing studies have evaluated the temporal trends of the normalized difference vegetation index (NDVI or vegetation greenness) in the North American boreal forest during the last two decades, often getting quite different results. To examine the effect that the use of different datasets might be having on the estimated trends, we compared the temporal trends of recently burned and unburned sites of boreal forest in central Canada calculated from two datasets: the Global Inventory, Monitoring, and Modeling Studies (GIMMS), which is the most commonly used 8 km dataset, and a new 1 km dataset developed by the Canadian Centre for Remote Sensing (CCRS). We compared the NDVI trends of both datasets along a fire severity gradient in order to evaluate the variance in regeneration rates. Temporal trends were calculated using the seasonal Mann,Kendall trend test, a rank-based, nonparametric test, which is robust against seasonality, nonnormality, heteroscedasticity, missing values, and serial dependence. The results showed contrasting NDVI trends between the CCRS and the GIMMS datasets. The CCRS dataset showed NDVI increases in all recently burned sites and in 50% of the unburned sites. Surprisingly, the GIMMS dataset did not capture the NDVI recovery in most burned sites and even showed NDVI declines in some burned sites one decade after fire. Between 50% and 75% of GIMMS pixels showed NDVI decreases in the unburned forest compared with <1% of CCRS pixels. Being the most broadly used dataset for monitoring ecosystem and carbon balance changes, the bias towards negative trends in the GIMMS dataset in the North American boreal forest has broad implications for the evaluation of vegetation and carbon dynamics in this region and globally. [source] Structure and composition of Acacia xanthophloea woodland in Lake Nakuru National Park, KenyaAFRICAN JOURNAL OF ECOLOGY, Issue 4 2006N. Dharani Abstract The woody vegetation of Lake Nakuru National Park occurs along rivers, lakeshores and flood plains. Four different sites within the Acacia xanthophloea woodlands were selected for the study. Vegetation structure was not significantly different in the four woodlands used for the study, but these sites differed in the relative density of Acacia trees. Regeneration of A. xanthophloea differed in each site, with the highest regeneration rates found in the nonfenced plots where browsing took place. Résumé La végétation ligneuse du Parc National de Nakuru se trouve le long des cours d'eau, sur les berges du lac et dans les plaines inondables. Nous avons sélectionné quatre sites dans les zones arborées àAcacia xanthophloea. La structure da la végétation n'était pas significativement différente dans les quatre forêts sélectionnées pour l'étude, mais ces sites différaient quant à la densité relative d'acacias. La régénération des Acacia xanthophloea différait sur chaque site, et le taux de régénération était le plus élevé dans les plots non clôturés fréquentés par les herbivores. [source] Change in sugar, sterol and fatty acid composition in banana meristems caused by sucrose-induced acclimation and its effects on cryopreservationPHYSIOLOGIA PLANTARUM, Issue 1 2006Guo-Yu Zhu To understand the mechanisms of sucrose-induced acclimation in relation to plant cryopreservation, sugars, sterols, fatty acids of different lipid fractions (neutral lipids, glycolipids and sphingolipids and phospholipids), as well as free fatty acids were analyzed in proliferating meristem cultures of different banana varieties. The four banana varieties that were selected show different post-thaw shoot regeneration rates (0,53.4%). All mentioned parameters were analyzed using (1) control meristems that were cultured on a normal sucrose concentration (0.09 M), which resulted in low survival after cryopreservation; and (2) 2-week sucrose precultured meristems (0.4 M). This sucrose preculture, essential for regeneration after cryopreservation, resulted in a significant increase of each of seven sugars detected. The ratio of stigmasterol/sitosterol (St/Si) in sucrose-pretreated meristems significantly increased. The sucrose pretreatment also resulted in a significant increase of total fatty acid content of the neutral lipid fraction and of the glycolipid and sphingolipid fraction, as well as the total free fatty acid content. The individual fatty acid content of the phospholipids was differently changed by the sucrose pretreatment for the given varieties studied. In most cases, sucrose pretreatment resulted in an increase of the double bond index (DBI) in the neutral lipids and a decrease of DBI in the glycolipids and sphingolipids, in phospholipids as well as in free fatty acids. Principal component analysis of all collected data revealed that (1) for the control material, sucrose and total sugar contents were closely linked to the post-thaw shoot regeneration, suggesting that sucrose and total sugar may be main limiting factors to survive cryopreservation; (2) accumulation of large quantities of sugars (glucose, fructose, sucrose and total sugar) in sucrose-pretreated material cannot explain the differences in survival after cryopreservation of the four banana varieties. We assume that a minimal amount of sugars is needed in meristem cultures to survive cryopreservation. Still, other limiting factors do influence the survival following the sucrose pretreatment. We observed that the parameters which are closely linked to the post-thaw shoot regeneration are a minimal change in the ratios of St/Si, the minimal change of the DBI of phospholipids and free fatty acids, as well as linoleic acid content (C18:2); and (3) inositol, raffinose, myristic acid (C14:0) and oleic acid (C18:1) were present in small quantities; however, they could be correlated to survival after cryopreservation, suggesting that they may be also involved in cryopreservation process. [source] | |||||||||||||